I hear your concern that SketchUp Make 2017 will no longer run on some future hardware/OS combination that you might either choose to buy or be forced into (via Software Update) by Apple. On the SketchUp team, we are worried about that, too. But I think we all have a long time to prepare for that eventuality.
I’m still running SketchUp 8 on the latest Apple hardware today. In fact, I’m still able to run older builds than that. I think I still have SketchUp 6 running somewhere, though I haven’t checked it recently. Given my long experience with Apple’s operating systems, I wouldn’t be surprised to find that I could still run our original OS X builds of SketchUp today, and they are more than fifteen years old.
You’ve seen me say in these forums many times that we predict a long life for SketchUp Make 2017. We build our code to last, and it isn’t uncommon to see folks running builds that are as much as eight to ten years old. If you’re careful about how you upgrade your hardware and OS, you can keep an old version running indefinitely.
Looking ahead ten years into the future, I can’t predict with any reliability what Apple’s OS strategy will create. But there’s no reason to expect that the hardware you have today won’t be able to run SketchUp Make 2017 tomorrow.